This invention relates generally to silicates and siliceous compositions, including siliceous minerals, such as aluminosilicates and the like, and more specifically relates to a method for chlorinating materials of this type in order to produce intermediates having new and unusual properties enabling subsequent functionalization thereof.
It has long been known to treat silicates, siliceous minerals and the like, with halides, specifically including gaseous chlorine, for the purpose of producing chlorides for various industrial and other applications. Clays, for example, are generally fine grained, earthy material made up of minerals which are essentially hydrous aluminosilicates. Numerous processes have been utilized for recovering aluminum from clays, which involve a chlorination step, and which are conducted at relatively very high temperatures. These processes generally produce aluminum chloride, which is further reacted to ultimately produce the desired aluminum.
In other instances, high temperature reactions of silicates or siliceous materials or minerals with chlorine have been utilized for the production of hydroxide-free silica for optical glasses. Additional prior art bearing upon the present invention include the following:
In Moore et al, U.S. Pat. No. 3,236,606, hot chlorine containing gaseous compounds are utilized in the bleaching of clay in a reactor in which fuel and air is present, and temperatures of the order of 600.degree. to 1200.degree. C.
British Patent Specification No. 894,383 teaches subjecting a kaolin clay to shock heating and thereafter to bleaching of same by treatment with chlorine gas at 700.degree. to 900.degree. C.
Nordberg, U.S. Pat. No. 2,141,444, discloses the use of carbon and chlorine in the course of removing iron from high alumina materials, including kaolin, kyanite, bauxite, diaspore, and the like, by heating the materials in the presence of the said components at temperatures of 900.degree. to 1150.degree. C.
Hall, U.S. Pat. No. 1,405,115, teaches the manufacture of aluminum chloride by contacting alumina, sulphur and chlorine at temperatures sufficient to yield the aluminum chloride and sulphur dioxide.
Hall, U.S. Pat. No. 1,422,568, teaches a process for manufacturing aluminum chloride which consists in maintaining an atmosphere of chlorine and sulphur vapors in a heated chamber and blowing a powdered aluminum compound thereinto.
Toth, U.S. Pat. No. 3,615,359, teaches a process for producing aluminum involving conversion of alumina under reducing conditions in the presence of carbon with manganese chloride to form aluminum trichloride and manganese, the reaction taking place in a first reaction zone the temperature of which is about 190.degree. C. at the inlet and 1400.degree. C. at the outlet of the zone, and then reacting the latter at a temperature of up to about 1400.degree. C., to reduce the aluminum trichloride to aluminum, by reacting the manganese with the said aluminum trichloride.
Willhoft, U.S. Pat. No. 4,073,872, discloses a process for recovering aluminum values from aluminum containing minerals such as bauxite and aluminosilicates, including kaolinite and the like. The aluminum containing mineral, together with carbon, is chlorinated to recover aluminum chloride. The process involves heating an intimate mixture of an aluminum-containing mineral and a solid carbonizable organic material, so as to carbonize the organic material, and chlorinating the solid residue from the carbonization step. The temperature of reaction may be up to 1500.degree. C., but is preferably slightly lower than the carbonization temperature, for example, in the range of 500.degree. C. to 800.degree. C.
Wyndham et al, U.S. Pat. No. 4,082,233, describes a method for carbo-chlorinating clay to produce aluminum chloride and silicon chloride. The clay is initially calcined with a solid carbonaceous reductant to form a reaction mass. Carbo-chlorination, in the presence of a sulphur-containing member, is conducted at temperatures within the range of from about 400.degree. C. to about 1000.degree. C.
Wyndham et al, U.S. Pat. No. 4,083,927, relates to further improvements for carbo-chlorination of clays which have previously been calcined. The reaction mixture during carbo-chlorination is in the temperature range of 600.degree. C. to 950.degree. C., using dry chlorine to which is added about 0.3% to 2.5% by volume of boron chloride.
Martin et al, U.S. Pat. No. 4,096,234, discloses the production of aluminum chloride from clay by chlorinating the clay through contact with a mixture consisting of a chlorinating agent, a reducing agent, an alkaline metal compound catalyst and silicon chloride. The chlorination process is carried out in a fluidized bed at a temperature of 550.degree. C. to 650.degree. C.
Wyndham et al, U.S. Pat. No. 4,139,602, relates to the preferential chlorination of alumina in kaolinitic ore feed materials to produce aluminum chloride. The process utilizes carbo-chlorination; the kaolin clay is initially dried, comminuted, and calcined in the temperature ranging from 500.degree. C. to 1000.degree. C. The carbo-chlorination is effected in the temperature range of from 600.degree. C. to 1000.degree. C.
Martin, U.S. Pat. No. 4,213,943, discloses a process for producing aluminum chloride from clay containing aluminum oxide and silicon oxide, by a 2-step chlorination process. Chlorination is effected at 550.degree. C. to 650.degree. C.
Dell, U.S. Pat. No. 4,244,935, discloses a method for chlorinating particles of a substance containing metal and oxygen, utilizing a coking step carried out in a temperature range of 450.degree. to 650.degree. C., followed by a heating step carried out between 700.degree. to 1100.degree. C.
Reynolds et al, U.S. Pat. No. 4,288,414, discloses a process for recovering aluminum from clays associated with coal or bauxite containing iron, siliceous material and titanium, comprising chlorinating the material at temperatures of from about 650.degree. C. to 900.degree. C., in an oxidizing atmosphere in the presence of added oxygen; and then chlorinating the residue from the said step with chlorine at a temperature of from about 600.degree. C. to 850.degree. C., in a reducing atmosphere of carbon monoxide.
Dunn, U.S. Pat. No. 4,355,007, discloses a two stage process for chlorinating aluminum value-containing materials such as bauxite, clay, etc. The material is dehydrated, and then chlorinated in the presence of chlorine and carbon at a temperature of below about 1200.degree. K. (temperature of about 1100.degree. K. is typical); oxygen is introduced, and thereafter the non-gaseous product is chlorinated in the presence of chlorine and carbon at a temperature above about 1300.degree. K.
U.S. Pat. Nos. 4,355,008 and 4,363,789, each to Dunn Jr. are similar to Dunn Jr. U.S. Pat. No. 4,355,007, to the extent that chlorination is involved in the course of producing aluminum from a material containing alumina values via chlorination.
In the instance of kaolin clays, it has long been recognized that products having new properties and uses could be formulated by combining these aluminosilicates with organic materials. However, any useful progress in this direction has tended to be limited by the lack of available covalent bonding at the mineral/organic interface. In the past this difficulty has been partially overcome by surface modification of the kaolinite through the use of various coupling agents--such as organotitanates, organosilanes, organo aluminozirconates, etc.
Thus, in Papalos U.S. Pat. No. 3,227,675, for example, kaolin clays are described, the surfaces of which are modified with organofunctional silanes. A typical such agent e.g. is a methacryloxypropyltrimethoxy silane. The kaolin clays so modified are advantageously used as fillers for natural and synthetic rubbers and the like. It is also pointed out in this patent that such modified products can serve as intermediates for synthesis of new pigments, which are useful as fillers for polymers, elastomers and resins. This result obtains because the silanes used to modify the kaolin clays are di- or polyfunctional, and only one functional group, the silane, is attached to the clay, leaving the remaining reactive groups to react further.
Additional references of this type include Iannicelli U.S. Pat. No. 3,290,165, and Iannicelli U.S. Pat. No. 3,567,680.
However, the modification of aluminosilicates such as kaolin clays by the use of organosilanes, is a complicated and expensive process. Among other things, the cost of the organosilane itself is very high. Furthermore, the resulting products have only limited capability for further functionalization, regardless of the particular organosilanes utilized.
In accordance with the foregoing, it may be regarded as an object of the present invention, to provide a relatively simple, inexpensive and effective process, which enables activation of the surfaces of clay minerals, to form reactive chloride intermediates, which are eminently capable of subsequent functionalization with organic groups and the like.
It is a further object of the invention to provide a process for reacting siliceous materials, such as clay minerals, with gaseous SiCl.sub.4, to activate the surface of same and thereby form reactive chloride intermediates, which process may be practiced on a very wide variety of such materials, including numerous types of clays, such as those of the kaolin group, montmorillonite group, illite group, etc.